1. Field of the Invention
The present invention relates to an image forming apparatus using an electrophotographic type of an electrostatic recording method. More particularly, the invention relates to an image forming apparatus, such as a copying machine, a printer, a multifunctional printer, or a facsimile apparatus, among others, and also, relates to a method for determining the status of attachment or detachment of the developer container which is detachably attachable to the image forming apparatus.
2. Related Background Art
For the image forming apparatus which adopts an electrophotographic method or the like, there has been known conventionally an image forming apparatus provided with a device for detecting residual developer to detect the remaining amount of toner in the developer container which stores developer (toner) as one example of the device for determining the status of a developer container.
For a device of the kind for determining the remaining amount of developer, there have been proposed various methods put in practice, such as the optical method that uses light emitting and photosensitive devices, the method that uses electrostatic capacitance method for detecting the electrostatic capacitance of developer, the piezoelectric method that detects the pressure of developer by means of vibration, and the method that uses a magnetic permeability sensor (toner sensor) for detecting the changes of magnetic permeability as voltage changes by the utilization of magnetism of developer, among others.
Also, for an image forming apparatus of the foregoing kind, there has been put in practice the image forming apparatus of cartridge type that the cartridge, which contains at least a developer container, is made detachably attachable to the main body fo the image forming apparatus, and the cartridge is replaced with a new cartridge when the developer in the developer container becomes less than a designated amount.
For a cartridge type of the foregoing kind, it is preferable to use repeatedly a residual developer sensor which serves as detecting means when cartridges are replaced.
Also, as an error indication to the user, there has been proposed a method for indicating the event that the developer (toner) in the developer container no longer exists (becomes less than a designated amount) or that the cartridge itself has not been inserted as yet (in a state of being detached) so as to enable the user to take adequate actions with ease accordingly. In this case, besides detecting means for detecting the presence or absence of toner in an amount more than a designated amount in the developer container of a cartridge, there is provided detecting means that uses a microswitch, a photosensor, or the like in order to detect the status of attachment of the cartridge (developer container) or detachment thereof.
Also, among those provided with detecting means to detect the status of attachment of a cartridge or detachment thereof, some of image forming apparatuses may cause the main body thereof to be damaged and put it out of order or the like if the image forming apparatus is allowed to execute a specific operation, while the cartridge is in a status of being detached. Here, therefore, the image forming apparatus of cartridge type should be arranged to be able to prohibit the operation thereof if the cartridge is found to be detached by the detection of the status of attachment or detachment of the cartridge. Thus, it is a prerequisite to detect and ascertain the status of attachment or detachment of a cartridge.
However, for the conventional image forming apparatus described above, a sensor dedicated to detecting the status of attachment or detachment of a cartridge is separately needed in addition to the sensor for detecting residual developer. This inevitably presents a problem of higher costs.
Also, if a photosensor, a microswitch. or the like should be used for detecting the status of attachment or detachment of a cartridge, there is a need for securing a space of the installation of such sensor or switch inside an image forming apparatus. In some cases, therefore, this arrangement may stand in the way of making the apparatus smaller.
Furthermore, in order to operate such sensor or switch, several numbers of components are additionally required or the configuration of a related component should be designed in a restricted manner. This may also hinder the implementation of lowering costs or making the apparatus smaller in some cases.
It is an object of the present invention to provide a method for determining whether a developer container is attached to an image forming apparatus by using detecting means for outputting information corresponding to a magnetic permeability of developer so as to detect a remaining quantity of developer in said developer container, said developer container having an agitating member provided with a magnetic member for agitating developer in said developer container, for agitating developer contained and being detachably attachable to the image forming apparatus without any separate provision of a sensor or the like dedicated to determining the status of the developer container attached to or detached from the main body of the image forming apparatus, while implementing to reduce the costs of the image forming apparatus, as well as to make the image forming apparatus smaller, and also, to provide such image forming apparatus. In other words, it is an object of the invention to provide a method for determining whether a developer container is attached to the main body of an image forming apparatus by use of detecting means for detecting information of the magnetic permeability of the developer in the developer container, and also, to provide such image forming apparatus.
Other objectives and advantages besides those discussed above will be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part hereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.